One illustration of a universe with this kind of topology is PacMan, in which a figure leaving through the left side of the screen reenters from the right. This was also the basis for the Doctor Who story Castrovalva. The Doctor is trapped in a sort of courtyard. Whenever he tries to leave the courtyard through one side he finds himself returning from the other.

Gary

Yes, I like it. Michio Kaku, “Parallel Worlds”, chap 5, “A Universe in Your Bedroom”. “In a Misner space, the entire universe is contained in your bedroom. The opposite walls are all identified with each other, so entering one wall you immediately emerge from the opposite wall. The ceiling is likewise identified with the floor. Misner space is often studied because it has the same topology as a wormhole but is much simpler to handle mathematically. If the walls move, then time travel might be possible within the Misner universe.” I love this stuff. And donuts.

C. Bauserman

I especially liked Saussure and Wittgenstein… Oh, those linguistic philosophers. So funny. ^_^

Marta L.

As I mentioned over at my FB page, only in an introductory philosophy course would you get Saussure, Wittgenstein, BOTH Nietzsche and Marx… but only one thinker in the 1,900 years between Aristotle and Descartes. Anselm would tell us the good human would rationally know it’s proper to love (eating) the donut. Aquinas would question whether the crumbs still constituted the same donut once they no longer partook in the same soul. Ockham would deny the existence of a universally real donutness. Marcus Aurelius would tell us not to rest our desires on a donut external to the self.